This invention relates to a device and method for making gloves, and specifically relates to an apparatus and methods for making a glove with thermobonded seams having fingers, a hand portion and a thumb portion that folds inwardly across the hand portion to provide better fit and to relieve stress at seams attaching the thumb portion to the hand portion.
Many prior art gloves have been manufactured using thermobonding around the periphery of the glove to define the finger and thumb portions attached to a hand portion. For example, U.S. Pat. No. 3,866,245 describes a plastic glove with a peripheral thermobonded seam and a precut liner inset and methods of making such a glove. A glove with a finely powdered coating to prevent sticking of the material except at its thermobonded seams is disclosed in U.S. Pat. No. 3,387,307. U.S. Pat. No. 3,147,493 discloses a thermobonded mitten or glove having a separate thumb crotch and a thermobonded seam across the palm at the level of the thumb crotch. U.S. Pat. No. 4,916,757 describes a thermobonded glove having peripheral sealed seams that define a thumb, forefinger and a mitten-like portion and a method of making the glove. Die-cut gloves made from a strip of film sealed around the glove periphery are severably connected by joining the finger of one glove to the wrist of an adjacent glove as described in U.S. Pat. No. 4,034,853. Similarly, thermobonding can be used to form other types of garments such as those described in U.S. Pat. No. 5,429,707.
A variety of thermobonding devices and methods to produce seams of gloves, mittens or other garments are known. For example, U.S. Pat. No. 4,555,293 and U.S. Pat. No. 4,776,921 disclose thermobonding plastic sheets by melting the material in a confined void zone located between a heating element and a pressure means. U.S. Pat. No. 3,028,576 discloses an apparatus and method of thermobonding seams and cutting away peripheral edges of gloves. An apparatus for thermobonding sheet material using cooperating die members and a vacuum to draw the sheet material to the die is described in U.S. Pat. No. 3,250,660. Another thermobonding device to seal and sever plastic films using a rapidly heated die is disclosed in U.S. Pat. No. 3,536,568. U.S. Pat. No. 5,244,525 describes a method of thermobonding and cutting sheets of polymer film by applying a xerographic toner in an outline of a seam and then exposing the toner to infrared radiation to melt the film U.S. Pat. No. 4,604,152 discloses a method of making a sealed waterproof seam by melting a thermoadhesive adjacent to a stitched seam. U.S. Pat. No. 4,643,791 and U.S. Pat. No. 4,804,432 disclose a device and methods for manufacturing thermobonded gloves by first forming a thermobonded thumb-shaped loop and then joining the thumb loop to the thermobonded fingers of a glove.
Many of the prior art devices and methods of manufacturing thermobonded gloves inefficiently utilize raw materials in the process, producing relatively large amounts of scrap. Moreover, some methods of removing scrap material cause stress on the glove materials, thus stretching and weakening of the materials or producing misalignment of materials in the process line resulting in substandard gloves and further wastage. Prior art devices and methods often require an additional step of cutting the wrist of the final glove to free it from the scrap material. Many thermobonding methods degrade the integrity of the thermoplastic materials by stretching the material during sealing which produces thinner weaker seams or intermittent weak points in the seams. Moreover, thermobonding devices are often susceptible to buckling during heating due to expansion of the heat element. Buckling is particularly a problem in contoured regions such as used to form a thumb or fingertips of a glove.
Gloves formed by peripheral thermobonded seams that define a thumb and fingers in a single plane limit hand movement because stress occurs across the back of the hand when the thumb and/or fingers are flexed. Such gloves inhibit free rotation of the thumb and produce stress points in the thermobonded seams, particularly at the crotch of the thumb and the fingers. Stress points tend to rip during glove usage, exposing the user's hands to hazardous materials or exposing the handled materials to contamination from the user's hands. To avoid glove stress and seam failure, users tend to wear gloves that are substantially oversized. Oversized gloves, however, present additional problems because they interfere with dexterity, bunch in the palm region and slip from the user's hand. Thus oversized gloves also risk exposing the user's hands to hazardous materials or entangling the glove material with machinery.
The gloves of the present invention overcome many of the deficiencies of the prior art gloves by allowing free rotation of the thumb relative to the fingers, thus relieving stress points in thermobonded seams and providing better fitting gloves. This eliminates the need to wear substantially oversized gloves. Moreover, the glove design lends itself to good manufacturing processes. Because substantially oversized gloves are not required by the user, the amount of thermoplastic material used to manufacture gloves suitable for the user is conserved. The methods of the present invention overcome many of the problems of the prior art by efficiently utilizing materials during glove production and eliminating the need for cutting the gloves at the wrist during manufacturing. Strong, even thermobonded seams are produced by using the improved thermobonding device of the present invention.